#!/usr/bin/env python3# SPDX-License-Identifier: GPL-2.0## Test that truncation of bprm->buf doesn't cause unexpected execs paths, along# with various other pathological cases.import os, subprocess # Relevant commits## b5372fe5dc84 ("exec: load_script: Do not exec truncated interpreter path")# 6eb3c3d0a52d ("exec: increase BINPRM_BUF_SIZE to 256") # BINPRM_BUF_SIZESIZE=256 NAME_MAX=int(subprocess.check_output(["getconf", "NAME_MAX", "."])) test_num=0pass_num=0fail_num=0 code='''#!/usr/bin/perlprint "Executed interpreter! Args:\n";print "0 : '$0'\n";$counter = 1;foreach my $a (@ARGV) {    print "$counter : '$a'\n";    $counter++;}''' ### test - produce a binfmt_script hashbang line for testing## @size:     bytes for bprm->buf line, including hashbang but not newline# @good:     whether this script is expected to execute correctly# @hashbang: the special 2 bytes for running binfmt_script# @leading:  any leading whitespace before the executable path# @root:     start of executable pathname# @target:   end of executable pathname# @arg:      bytes following the executable pathname# @fill:     character to fill between @root and @target to reach @size bytes# @newline:  character to use as newline, not counted towards @size# ...def test(name, size, good=True, leading="", root="./", target="/perl",                     fill="A", arg="", newline="\n", hashbang="#!"):    global test_num, pass_num, fail_num, tests, NAME_MAX    test_num += 1    if test_num > tests:        raise ValueError("more binfmt_script tests than expected! (want %d, expected %d)"                         % (test_num, tests))     middle = ""    remaining = size - len(hashbang) - len(leading) - len(root) - len(target) - len(arg)    # The middle of the pathname must not exceed NAME_MAX    while remaining >= NAME_MAX:        middle += fill * (NAME_MAX - 1)        middle += '/'        remaining -= NAME_MAX    middle += fill * remaining     dirpath = root + middle    binary = dirpath + target    if len(target):        os.makedirs(dirpath, mode=0o755, exist_ok=True)        open(binary, "w").write(code)        os.chmod(binary, 0o755)     buf=hashbang + leading + root + middle + target + arg + newline    if len(newline) > 0:        buf += 'echo this is not really perl\n'     script = "binfmt_script-%s" % (name)    open(script, "w").write(buf)    os.chmod(script, 0o755)     proc = subprocess.Popen(["./%s" % (script)], shell=True,                            stdout=subprocess.PIPE, stderr=subprocess.STDOUT)    stdout = proc.communicate()[0]     if proc.returncode == 0 and b'Executed interpreter' in stdout:        if good:            print("ok %d - binfmt_script %s (successful good exec)"                  % (test_num, name))            pass_num += 1        else:            print("not ok %d - binfmt_script %s succeeded when it should have failed"                  % (test_num, name))            fail_num = 1    else:        if good:            print("not ok %d - binfmt_script %s failed when it should have succeeded (rc:%d)"                  % (test_num, name, proc.returncode))            fail_num = 1        else:            print("ok %d - binfmt_script %s (correctly failed bad exec)"                  % (test_num, name))            pass_num += 1     # Clean up crazy binaries    os.unlink(script)    if len(target):        elements = binary.split('/')        os.unlink(binary)        elements.pop()        while len(elements) > 1:            os.rmdir("/".join(elements))            elements.pop() tests=27print("TAP version 1.3")print("1..%d" % (tests)) ### FAIL (8 tests) # Entire path is well past the BINFMT_BUF_SIZE.test(name="too-big",        size=SIZE+80, good=False)# Path is right at max size, making it impossible to tell if it was truncated.test(name="exact",          size=SIZE,    good=False)# Same as above, but with leading whitespace.test(name="exact-space",    size=SIZE,    good=False, leading=" ")# Huge buffer of only whitespace.test(name="whitespace-too-big", size=SIZE+71, good=False, root="",                                              fill=" ", target="")# A good path, but it gets truncated due to leading whitespace.test(name="truncated",      size=SIZE+17, good=False, leading=" " * 19)# Entirely empty except for #!test(name="empty",          size=2,       good=False, root="",                                          fill="", target="", newline="")# Within size, but entirely spacestest(name="spaces",         size=SIZE-1,  good=False, root="", fill=" ",                                          target="", newline="")# Newline before binary.test(name="newline-prefix", size=SIZE-1,  good=False, leading="\n",                                          root="", fill=" ", target="") ### ok (19 tests) # The original test case that was broken by commit:# 8099b047ecc4 ("exec: load_script: don't blindly truncate shebang string")test(name="test.pl",        size=439, leading=" ",     root="./nix/store/bwav8kz8b3y471wjsybgzw84mrh4js9-perl-5.28.1/bin",     arg=" -I/nix/store/x6yyav38jgr924nkna62q3pkp0dgmzlx-perl5.28.1-File-Slurp-9999.25/lib/perl5/site_perl -I/nix/store/ha8v67sl8dac92r9z07vzr4gv1y9nwqz-perl5.28.1-Net-DBus-1.1.0/lib/perl5/site_perl -I/nix/store/dcrkvnjmwh69ljsvpbdjjdnqgwx90a9d-perl5.28.1-XML-Parser-2.44/lib/perl5/site_perl -I/nix/store/rmji88k2zz7h4zg97385bygcydrf2q8h-perl5.28.1-XML-Twig-3.52/lib/perl5/site_perl")# One byte under size, leaving newline visible.test(name="one-under",           size=SIZE-1)# Two bytes under size, leaving newline visible.test(name="two-under",           size=SIZE-2)# Exact size, but trailing whitespace visible instead of newlinetest(name="exact-trunc-whitespace", size=SIZE, arg=" ")# Exact size, but trailing space and first arg char visible instead of newline.test(name="exact-trunc-arg",     size=SIZE, arg=" f")# One bute under, with confirmed non-truncated arg since newline now visible.test(name="one-under-full-arg",  size=SIZE-1, arg=" f")# Short read buffer by one byte.test(name="one-under-no-nl",     size=SIZE-1, newline="")# Short read buffer by half buffer size.test(name="half-under-no-nl",    size=int(SIZE/2), newline="")# One byte under with whitespace arg. leaving wenline visible.test(name="one-under-trunc-arg", size=SIZE-1, arg=" ")# One byte under with whitespace leading. leaving wenline visible.test(name="one-under-leading",   size=SIZE-1, leading=" ")# One byte under with whitespace leading and as arg. leaving newline visible.test(name="one-under-leading-trunc-arg",  size=SIZE-1, leading=" ", arg=" ")# Same as above, but with 2 bytes undertest(name="two-under-no-nl",     size=SIZE-2, newline="")test(name="two-under-trunc-arg", size=SIZE-2, arg=" ")test(name="two-under-leading",   size=SIZE-2, leading=" ")test(name="two-under-leading-trunc-arg",   size=SIZE-2, leading=" ", arg=" ")# Same as above, but with buffer half filledtest(name="two-under-no-nl",     size=int(SIZE/2), newline="")test(name="two-under-trunc-arg", size=int(SIZE/2), arg=" ")test(name="two-under-leading",   size=int(SIZE/2), leading=" ")test(name="two-under-lead-trunc-arg", size=int(SIZE/2), leading=" ", arg=" ") print("# Totals: pass:%d fail:%d xfail:0 xpass:0 skip:0 error:0" % (pass_num, fail_num)) if test_num != tests:    raise ValueError("fewer binfmt_script tests than expected! (ran %d, expected %d"                     % (test_num, tests))